Blueprint



Patented July 30, 1,940

BLUEPRIN T Donald E. Whitlock, Orange, and John F. Kienast, Union City, N. J., assignors to Keulfel & Esser Company, Hoboken, N. J., a corporation of New Jersey No Drawing. Application August 18, 1937, Serial No. 159,710

Claims. (01. 95-7) This invention relates to solutions of light sensitive compounds, particularly to blueprint solutions and to the papers or cloths produced -by the application of such solutions to such bases.

The usual method of preparing light sensitive paper such as blueprint paper comprises the preparation of a solution of the proper composition, comprising photo-sensitive salts, which is then applied to a paper base and in some cases to cloth. After application, the paper is dried and is then ready for use. Frequently such paper is stored in light proof wrappings for relatively long periods of time before exposure and washing,'and 15 as a result of storage undergoes some chemical and considerable physical change before it is used. When paper is freshly prepared, the coating on the paper being water soluble can usually be readily washed out. However, many blueprint solutions do not have good initial washing out properties, and as the papers age the washing out becomes'more and more diflicult. This is an important factor in the successful use of the paper, because when the paper is exposed and those portions which are subjected to the action of light are changed by the photo chemical re-' action, it is important that the salts on the unexposed portions which are not aflected by so the light shall be completely washed from the paper to give the proper white as a contrast with the blue.

A great deal of work has been done in order to produce a blueprint paper which could be satis- 35 factorily washed out, either as originally prepared or after it has aged.

The latter property may be designated as the keeping quality of the paper, which is the characteristic of the coating that permitsit to be cleanly washed off the aged paper, after exposure, from those portions which have not been exposed to light.

We have discovered a way for improving blueprint solutions whichhas a substantial beneficial effect on the actual keeping qualities of the paper and which also improves the initial washing out.

A blueprint solution which we have found is normally quite successful has the following compositions:

" Ferric ammonium citrate lb Ferric ammonium oxalate lbs 3 Ferric sodium oxalate lb 1 oxalic acid o2s 2 Potassium ferricyanide ozs 55 Water gals 3 The paper coated with this solution has what would heretofore have been considered a fairly satisfactory washing-out quality. either when freshly prepared or when aged, but did have considerable apparent deterioration upon aging.

When this solution was modified by increasing its specific gravity approximately 1 degree Baum by the addition of a sugar, the properties of the solution and of the papers prepared by coating them with this solution were markedly improved along the lines above indicated. Specifically, in

the above formula, approximately 14 ozs. of

and after the coating had been applied to thepaper it could be readily washed off completely. Paper coated with such a solution has very good keeping quality. In other words, the coating could still be completely washed off from fairly old paper to produce pure whites in unexposed areas.

Various types of sugars, either alone or in combination, have been employed within that class generally known as monosaccharides and disaccharides, which are crystalline, soluble, and sweet carbohydrates. Included within this general class are those compounds known as glucose, dextrose, fructose, manose, galactose, maltose, lactose, as well as sucrose above mentioned, which includes both cane and beet sugar.

Sugars of the type above set forth have been used with various modified-blueprint solutions, and it has been found that when the sugars are added in an amount sufficient to increase the specific gravity of the blueprint solution from about Baum to approximately 2. Baum that the results suggested above are obtained.

The exact composition of the basic blueprint solution or its pH value does not seem to materially affect the results obtained through .the addition of sugar. The advantages above set forth have been noted with various blueprint solutions of the type set forth and other known types of blueprint solution. Another solution is Water gals 3 It will thus be seen that the invention is applicable to blueprint solutions generally.

While we have described our invention with reference to certain embodiments thereof, these are to be considered illustrative of the invention and not in limitation of it, the scope of the invention being outlined in the appended claims.

What is claimed is:

1. A base material coated with a solution containing both photo sensitive iron salts which react to form a blue upon exposure to light and development with water, and a sugar forming from 5% to 20% of the solid content of the solution.

2. Blueprint paper or cloth coated with a solution containing both photo sensitive iron salts which react to form a blue upon exposure to light and development with water, and'a sugar forming from 5% to 20% of the solid content of the solution.

3. A light sensitive coated paper readily washed out when initially prepared, and having good keeping quality comprising a paper base having a coating thereon of both photo sensitive iron and iron cyanogen salts and a sugar, the sugar forming from about 5% to 20% of the coating 4. A light sensitive coated paper readily washed out when initially prepared, and having good keeping qualities comprising a paper base having a coating thereon of both photo-sensitive ferric salts and a soluble iron cyanide salt and a sugar, the sugar forming from about 5% to 20% of the coating, o

5. A blueprint solution containing photo-sensitive iron salts comprising a ferric salt and a ferricyanide, both soluble in water, and a sugar in an amount sufficient to increase the specific gravity from to 2 Baum.

DONALD E. WHITLOCK. JOHN F. KIENAST. 

